An embodiment of the invention taught by the above-referenced U.S. patent application Electroluminescent System in Monolithic Structure (the "Previous Invention") is directed to an electroluminescent ("EL") system having a unitary carrier whose layers form a monolithic structure. A preferred unitary carrier in this system is a vinyl resin. One of the advantages of this monolithic electroluminescent system is that the layers thereof may be printed down as inks in a screen printing process onto a wide variety of substrates.
It is also known in the art that elastomeric structures have unique and useful properties. Behaving much like sturdy membranes, the malleability and ductility of elastomeric structures enable applications that would otherwise be unavailable to more rigid or plastic components.
There are many potentially advantageous applications of an elastomeric electroluminescent ("EL") lamp. For example, highly pliable and resilient backlit keyboard facia would be enabled in cellular telephones or other personal communications devices. Alternatively, lamp sections in membranous elastomeric form could be printed down onto selected sections of the telephone case itself. These sections could be caused to illuminate as part of a visual alert energized when the telephone rings.
Alternatively, elastomeric EL lamps could be constructed in transfer form and then affixed to fibrous substrates, such as fabric. Experimentation has shown that screen printing down EL systems in accordance with the Previous Invention on substrates such as fabric often requires pre-preparation of the substrate for best results. First, the fabric may not always be optimally chemically compatible with the first layer of the EL system. Second, fabric fibers have been found to tend to "stand up" and interfere with an even and uniform print down of the EL system. As a result, although the Previous Invention has been found to be fully functional on such fabrics, the quality of electroluminescence can suffer. It has therefore been found advantageous to preprint a "platform layer" of the unitary carrier (with no EL-active ingredients) onto fabric and similar substrates to inhibit these factors. The EL system is then printed down onto the platform layer in accordance with the Previous Invention.
Although providing this platform layer tends to enhance the performance of the EL lamp, it will be understood to be an additional manufacturing step with attendant time, material and manufacturing process costs.
Moreover, further experimentation with printing down the EL system according to the Previous Invention has also shown that printing works best when the area to receive the printing is flattened out into a plane. For fabric printing, for example, this "flattening" is easily accomplished with garments such as t-shirts, but is not so easy with other garments, such as jackets or baseball caps, for which a "flattening" step may damage or detract from the final appearance of the garment.
There is therefore a general need in the art for elastomeric EL lamps. Such elastomeric lamps would be advantageous as components in products requiring flexible backlighting or visual alert lighting. Alternatively, in transfer form, such elastomeric lamps could enable improved application of the EL system of the Previous Invention to fibrous substrates, including fabrics, without incurring the additional cost and manufacturing step of pre-preparing the substrate to receive the EL system. Elastomeric EL lamps could also facilitate application of the EL system of the Previous Invention less traumatically to substrates with three-dimensional shapes.